Apparatus for making strip wound magnetic cores



y 1939- J. c. GRANFIELD 2,160,589

APPARATUS FOR MAKING STRIP WOUND MAGNETIC CORES Y Filed Jan. 30, 1937 2Sheets-Sheet l Inventor John C. Granfield y Wan/1 6.,

HLS Attowneg,

May 30, 1939. J. c. GRANFIELD APPARATUS FOR MAKING STRIP WOUND MAGNETICCORES Filed Jan. 30, 1937 2 Sheets-Sheet 2 Ifwevfliov v John C.Gvanfield m7 III HIS Attorney.

Patented May 30, 1939 UNITED STATES APPARATUS FOR MAKING s'mrr WOUNDMAGNETIC corms John C. Graniield, Pittsfield, Mass" assignor to GeneralElectric Company, a corporation of New York Application January 30,1937,Serial No. 123,250

10 Claims.

In my copending application, Serial No. 123,249,

filed concurrently herewith,.I have disclosed and claimed certainimprovements in electro-magnetic induction apparatus such astransformers and reactors, and the method of making the same, and I havedisclosed but not claimed therein the machine for making such apparatus,such machine constituting subject matter claimed in the presentapplication. This application, like the application filed concurrentlyherewith, is a continuation-in-part of my application, Serial No.77,499, filed May 2, 1936.

My invention relates particularly to a machine for applying strip woundmagnetic cores to transformers, reactors and the like. In accordancewith the method disclosed in my copending applications the strip woundcore is adapted to be applied to form wound conductive windingstructures. My machine is adapted to apply strip -01? variouscomposition and thickness. One kind of strip which may be very easilyapplied by my machine is strip of high reduction cold-rolled siliconsteel containing about 3% silicon. This strip may be obtained from themill in long 5 lengths and long lengths may also be made by weldingshorter strips end to end. In accordance with the method disclosed in myapplications, the strip is wound spirally to form a hollow cylindercontaining the exact amount of magnetic material required for one of thespirally w und core elements of a transformer. The inside and outsidedimensions of the tightly wound coil of strip are made exactly the sameas the dimensions that the completed core element is to have in thetransformer. After such a coil of strip has been wound the end of theoutside turn of the strip is secured to the next underlying turn ofstrip, preferably by tack welding it thereto, and the coil of magneticstrip in this form is placed in a heat treating oven which gives thecoil of strip a permanent set. The high reduction. cold-rolled siliconstrip has the most favorable magnetic orientation of the grain in thedirection in which the strip has been rolled. The heat treatment of sucha coil of strip for at least an hour at a temperature of about 800 C. toabout 900 C. in the heat treating oven assists in developing thefavorable magnetic characteristics of the strip as well as g ving it aperform a loop having a circumference considerably greater than theoutside circumference of the heat treated coil. The end of the strip ofthe large loop is secured-to the next underlying turn of the stripwhereupon, by rotation of the heat treated coil together with the largeloop, the strip is unwound from the heat treated coil and wound on theinside of the large loop. After all of the strip has been coiled intothe larger loop the tack weld is loosened and the. larger loop collapsedupon the leg of the conductive winding structure, and in the completedcore element the coil of strip has the exact dimensions that it had whenheat treated. In accordance with such method of application, the

strip can be applied so that when the core element has been completed itis free from elastic strains which would impair its magnetic qualities.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawings in which Figs. 1 and2 show an early step in the application of a coil of magnetic strip to atransformer, the figures being alike except that they show differentconstructions of the transformer conductive windings; Fig. 3 shows anintermediate step of the operation; Fig. 4 showsa later step in theoperation, and Fig. 5 shows the final step in the operation of windingthe strip on to the transformer; Fig. 6 shows in perspective with partsbroken away, one form of machine embodying my invention; Fig. 7 is aview taken generally from the left of Fig. 6 showing parts of themachine; Fig. 8 is a perspective view showing certain elements of themachine; Fig. 9 is a view showing a part of the machine of Fig. 6; .andFig. 10 shows a detail of one of the elements of the machine.

Referring to Fig. 1, a transformer conductive winding structure to whicha coil of magnetic strip is to be applied is shown in cross-section. Thewinding structure shown in Fig. 1- is of the general type shown inperspective in Fig. 6. This transformer comprises for example a primarywinding i0 and two secondary windings II and I2 located concentricallywith the primary winding, the windings H and I2 being. respectivelyoutside and inside of the winding Ill. The window through which thestrip is to be carried and wound about the right-hand leg of Fig. 1 isindicated at 13." The sides of the winding structure or winding legs asthey may be called are each provided with suitable insulation havingcircular contour, such insulation being inbe applied is shown at I5.

dicated at l4. The coil of magnetic strip to In the stage of operationshown in Fig. 1 the end of the coil of strip has been carried throughthe window l3 in the direction of the long arrow and curved into theform of a large loop I 6' and secured to the next underlying turn ofstrip, .as for example by tack-welding, at H. In my machine the coil ofstrip I5 is placed over a roller l3 engaging-the inside of the coil, anda roller I3 is provided to engage the outside of the coil. Ashereinafter described, means are provided for biasing the roller [3toward the roller l9 so that the coil of strip is gripped between theserollers which are provided with surfaces of rubber or the like to reduceslipping. The rollers l8 and I! are driven simultaneously and inopposite directions, as indicated by the arrows shown on the rollers inthe drawing. The rotation of the rollers turns the coil of strip I5 andturns the large loop IE to unwind the coil of strip i 5 andsimultaneously rewind the strip into the larger loop l6, turns of strip.being successively added to the inside of ftheloop l6. To facilitatethreading the strip through the window i3 and for another purposehereinafter described, a guide plate 20 is provided. For a generallysimilar purpose, a roller 2| is provided to bear against the outside ofthe loop ii. To prevent any tendency of the strip to climb up betweenthe rollers l3. and is during the winding operation, a roller 22 isprovided bearing on the top edge of the coil I 5 and the top edge of thelarger loop l6.

The showing of Fig. 2 differs from Fig. 1 only in.that the arrangementof the winding structure of the transformer to which the coil of stripis to be applied is somewhat different. In Fig. 2, the secondarywindings II and I2 are located one on each side of the primary windingID instead of concentrically on the inside and outside of the primarywinding. Both winding structures illustrated give a substantiallycruciform cross-section to the winding leg, the periphery having astepped form approximating a circle. Fig. 3 shows a stage in theoperation where nearly all of the strip has been unwound from the coill5 and rewound into the large loop It. It will be observed that thenumber of layers of strip in the larger loop I6 is only about half asgreat as the number of layers originally in the coil IS. The inside ofthe larger loop turns freely through the window l3 even though a numberof layers of strip have been placed within the outside turn of the loopl6. When the stage of operation shown in Fig. 3 is reached, a littlefurther rotation of the rollers l8 and I9 releases the inside end of thestrip which tends to curl around the insulating cylinder [4. The

operator may catch the end of the. strip by hand and hook it over theinsulating cylinder l4 if it should fail to assume that position. Theoperator then removes the roller l8 and loosens up the tack weld I!which he may do by a screw driver or other implement. The large loop, byreason of the resiliency of the strip and its tendency to assume theposition it occupied when heat treated, collapses to the generalposition shown in Fig. 4. The strip would assume a still more closedform if it were not for the friction of the edge of the strip'upon thetable upon which the winding operation is carried out.

The operator then secures the inside end of the strip to the insulatingcylinder I4 which he may conveniently do by clamping it by a smallclamp. He then brings the oppositely rotating limited by the guide plate23. The loop II, by

the rotation of the rollers 23 and 24, is rapidly collapsed and the sideof the loop touches the guide plate 20 only during the first fewrevolutions of the loop. The collapsing loop is followed up by theinward movement of the rollers 23 and 24 and .in a very short time theloop is collapsed to its completed form as shown in Fig. 5 at 25. Thecollapsing of'the loop is assisted by the permanent set given the stripin the heat treating oven and since the outside diameter of the cylinderof insulation l4 was made exactly the same as the inside diameter of theheat treated coil IS, the completed coil of strip 25 remains in thecompleted-position after the rollers 23 and 24 are removed. The outsideend of the strip may then be tack welded to the next underlying' turn ofstrip at 23. The turns of strip in the completed coil 25 are in the samesequence that they werein the heat treated coil I5. In accordance withthe method of applying the strip, it has not been strained beyond theelastic limit and the completed magnetic core is free from strains whichwould impair its permeability or watt loss characteristics.

Referring to Fig. 6, a completed transformer is shown in which two cores26 and 21 of magnetic strip have been applied to a winding structure.The tack-welds securing the outer end of the strip of the core 28 areindicated at 23. The transformer is ready to be lifted out of themachine preparatory to inserting a new winding structure to whichmagnetic cores are to be applied. The rollers l3 and I! described inconnection with Figs. 1 and 3 are shown in Fig. 8, the roller l9 alsobeing shown in Fig. 6. The guide roller 2| heretofore referred to forguiding the side of the large loop of strip is shown in Fig. 8 mountedon a member 29 adapted to be adjusted along the table 30 and clamped inany adjusted position by a wing nut 3'. The roller 22 heretothey may beswung toward and away from each other.

Before describing in greater detail the means for operating the variousrollers, it will be helpful to describe how the winding structure towhich the magnetic cores are to be applied is mounted on the machine andmoved to the proper position for application of the strip cores. In themachine shown in Fig. 6, the transformer is clamped between four lowerrollers 35 and four upper rollers 36. These rollers are preferablyprovided with a surface such as rubber so that they will not damage thetransformer windings. The four lower rollers are mounted on a plate 31pivotally supported as hereinafter described and the upper rollers 36are mounted on a plate 33 which is pivotally mounted on a threaded rod33 adjustable by a hand-wheel 40. The rod 33 is threaded .hand wheel 46to lift the upper clamping rollers I is pivotally mounted.

- For simplicity in description I shall refer to the supporting member42 with the parts mounted on the upper and lower'projecting portions 4|and 46 as the winding head. In the stage of operation shown in Fig. 6the transformer has been finished. To release it the operator turns the66 out-of engagement with the transformer windings. The transformer isthen lifted out of the machine and another transformer winding structureto which magnetic cores are to be applied is placed so as to besupported by the lower rollers 35. The hand wheel 46 is then turnedtolower the plate "carrying the upper rollers 36 to clamp the windingstructure in place between the upper and lower rollers. The upper plate36 is prevented from rotation when the rod 39 is rotated bythe handwheel 46, by a slidable rod 44 which carries a projection entering anopening in the member 36. There is an opening 45 in each end of thismember. By raising the rod 44 sufficiently to lift the projection out ofone of the openings 45 in the plate, the winding structure may be rotated upon the pivotal mountings of the plates 31 and 3Lthrough 180, andit may be held in its new position by the entrance of the projection onrod 44 into the other opening 45.

After the winding structure has been mounted in the winding head asdescribed it must be moved down into the table 36 a sufficient distanceto bring the point on the winding structure where the bottom edge of thestrip core is to be placed even with the surface of the table 36. Topermit this vertical movement the supporting member '42 of the windinghead is arranged to be moved vertically'on a support 46 which may beclamped in position on the table 36 as hereinafter described. Guidingroiiers 41 mounted on the supporting member 42' engage the side edges ofthe support 46 and rollers 46 mounted on the forwardly projecting-member4| bear on the back of the support 46. A rack 49 is welded to the edgeof the supporting member 42 and a pinion 56 operated by hand wheel 5|engages this rack to move the member 42 along the supporting member 46.The shaft for the pinion 56 and hand wheel 5| is mounted at the top of asupport 52 secured to a member adapted to slide along and be clamped tothe table 36 as hereinafter described. A clamping member 53 threadedinto the member 42 and moving in a slot 54 in the member 46 is providedto clamp the member 42 to the member 46 in any adjusted position. Whenthe operator wishes to lower the winding head, he loosens the clampingmember 53 and operates a lever 55 to move a dog 56 away from the rackwhereupon he can turn the hand wheel and lower the winding head into thetable to the desired position. The lever 55 is operated to engage'thedog 56 with the rack 46 and the operator then clamps the members 42 and46 together by the clamping member 53.

After having lowered the winding head to bring the conductive windingstructure of the transformer into the proper position with respect tothe top of the table 36, the operator lays the heattreated coil ofmagnetic strip to be applied to the transformer upon the table top andinserts the ro1ler|6 into the coil. To permit the roller Hi to beinserted and removed, it is provided with a projection 51 which enters adriving socket 56 rotatably mounted in' a member 56, as shpwn in Fig. 8.The roller is provided with a collar 66 entering the'socket 56. Theedges of the socket are slotted and a pin 6| through the collar 66enters the slots in the socket to provide a driving connection betweenthe member 56 and the roller l6. The top of the socket 56 appears inFig. 6'. To enable the roller |6 to be inserted in the coil ofstripplaced on the table, it is necessary to move the socketed member 56away from the roller I 6. To enable this to be done. the member 59 inwhich the socketed member 66 rotates is mounted on rods 62 and 56sliding in bearings in the table 36. The outer ends of these rods areconnected by a crosspiece 64. This cross-piece 64 has an opening throughwhich a guide pin 65 mounted ona member 66 secured to the table 66projects so that the pin 65 guides the cross-piece 64, preventing therods 62 and 63 from binding in the bearings of the table 36. Springs 61and 66 are provided on the rods 62 and 63 between the table 36 and thecross-piece 64 to bias theroller |6 toward the roller l6 by biasing themember 56 carrying the driving socket 56 toward'the right in Fig. 6. Tomove the socket 56 away from the roller I! to permit the insertion of.the roller II, the operator raises a lever 66 which moves the outer endof a crank 16 downwardly.- The outer end of this crank is secured to acable or chain H passing over a pulley I2 and secured to the cross-piece64. Raising the lever 66 therefore 1 moves the cross-piece 64 and rods62 and 63 to the left in Fig. 6, .thus moving the supporting member 59carrying the socket member 56 to the left. A pawl 13 is moved intoengagement with teeth 14 on a member on the shaft of the lever 69 andcrank 16 to hold the socket 56 in the position to which it has beenmoved against the b as of the springs 61 and 66.

After the operator has placed the roller I6 in position in the coil ofstrip and threaded the strip through the window in the winding structureand formed the large loop l6, as described 1 and 2. The roller 19 ismounted in a bearing in the table 36 and is driven by a pinion which isin turn driven by a gear '16 as shown in' Fig. 8.

The gear 16 is mounted at the top of a shaft I? which in the machineshown in Fig. 6 is driven through bevel gears 16 by a motor 19 operatingthrough pulleys and a belt 86 and a friction clutch 6|. The clutch is ashifting .clutch controlled by a foot lever 82.

The roller I 6 as shown more clearly in Fig. 8 is driven by the pinion12 through gears 63 and 64, the gear 84 engaging a gear 85 at the lowerend of the socketed member 58 turning in the member 59. The axis of thegear 83 is fixed to the table 36. The gear 64 is floatingly mounted topermit horizontal movement of the gear 65 when the member 59 is shiftedto move the position of,the socket 56 as heretofore described. To

permit of this floating movement the gear 64 is mounted between linkswhich are pivoted respectively on the axes of the gears 63 and 64,

era I3 and I9 for the strip'winding operation,

' the operator places the roller '22 in place to bear on the upper edgesof the strip as heretofore described in connection with Figs. 1 and 3.

'When'the coil of strip has been unwound into the larger loop justbeyond the position shown in Fig. 3, the operator stops the rotation ofthe rollers II and I9 andremoves the roller I8, whereupon the sta'iptakes the position shown in Fig. 4. The operator then breaks the tackweld securing the outer end of the strip tothe next underlying strip,secures the end of-tne inside turn to the in; sulating cylinder I4 asheretofore described, and brings the rollers 23 and 24 into position tocollapse the strip. To bring the rollers 29 and 24 into this positiomtheoperator moves the lever 93 which through the link 99 and a link whichdoes not, appear; in Fig. 6 turns the member 90 pivoted at its center at9I. The ends of the member 99 are connected through members 92 and 93 tomembers which swing the rollers 23 and 24 into and out of position.These rollers 23 and 24 are mounted at the outer ends of arms 94 and 95pivoted at the back of the machine, the pivot point for, the arm .94being shown at 93. l 'he members 92 and "operated from the lever 99 asheretofore described, swing the arms 94 and 95 about their pivot points.The connection between the member 92 and the arm 94 is indicated v at91, the member 91 being rigidly secured to the lower member of the arm94. This lower' member of the arm 94 does not appear in Fig. 6

but the lower member of the arm 95 is shown in Fig. 6.

To rotate the rollers 23 and 24, belts 99 and 99 are provided operatingover pulleys. The.

driving pulleys are-mounted on the axes of the pivoted arms and driventhrough suitable gear m'eclianism.

The gear mechanism for driving the pulleys on the arm 94 consists of apair of bevel gears I00 .provided for driving the roller 23, but thegears do not appear in the drawings except that a pinion I05 on thedriving shaft I99 and engaging the'gear- I04 does appear in Fig. 8.

The strip being in the position shown in Fig. 4 and the rollers 23 and24 moved against the strip, as shown in Fig. 4, the rotation of therollers collapses the strip to its completed position shown in Fig. 5,as heretofore described. To follow up the collapsing loop, the operatorcontinues to move the lever 99 to swing the arms 94 and 95'inwardly. Toprovide a gentle and yielding engagement of the rollers 23 and 24 withthe loop of strip, the members 92 and 93 are preferably constructed asshown in Fig. 10. These members comprise a cylinder I" in which aplunger I09 moves. A spring I09 is provided tending to'move the plungerout of the cylinder. The construction provides a kind of yieldingdash-pot connection.

I19 through the plunger III in the cylinder..

To an partially the opening in the table top The relative motion of theplunger and the cylinderis by a whifli moves of one of the magneticcores upon the trans-- former, he lifts the winding head by operatingthe hand-wheel 5|, as heretofore described. The winding head is securedin its upper position by the dog 59 engaging the rack 49, whereupon theoperator lifts the rod 44 and turns the winding structure through 180degrees, as heretofore described, at which position the rod 44 engagesthe opening in the other end of the member 33. The operator then lowersthe winding head to the proper position and proceeds to apply the othercore to the winding structure in the manner heretofore described.

To accommodate various sizes of winding structures and to adjust thedistance between the winding structure and the rollers I8 and II forvarious diameters of the large loop IS, the winding head is made bodilymovable longitudinally of the table. To accomplish this forward andbackward movement, a hand-wheel H4 is prm vided which operates pinionII5 engaging a rack IIG secured to the member III which slides on thetable top 39 as is more clearly shown in Fig. 7.

To clamp the winding head to the table in any adjusted position a member-I I II is provided which extends through thelower part of the support43v and is threaded into a plate I I9 bearing on 'the bottom surface ofthe table top. When the member H9 is tightened, the table top is clampedbetween the members I I I and H9. Since the transformer mounted in thewinding head is heavy and since all of its weight is in front of thewinding head, the winding head tends to tip forwardly which tendencywould cause the members I I1 and I I9 to bind on the table topinterfering with free in adjusted position by a longitudinal adjustmentof the winding head.

To overcome this tendency a member I 20 is bolted or otherwise securedto the member I" and this member L20 has two forwardly projectingmembers one of which is shown at I2I. At the forward ends of thesemembers I 2| rollers are mount ed, one of which is shown at I22 in Fig.6. These rollers bear upon tracks on the supporting plate I24. One-ofthe tracks is shown at I23. The supporting plate I24 also supportsvarious parts of the mechanism heretofore described including table so.a

While I have shown a particular construction of machine which I havefound well adapted for the purpose described, it will be apparent tothose skilled in the art that many changes and modiflcations may be madewithout departing from the spirit and scope of my invention and Itherefore aim in the appended claims to cover all such changes andmodifications.

7 What I claim as new and desire to secure by Patent of the UnitedStates is: 1 A'machine for applying strip wound magnetic cores towinding structures comprising means for holding the winding structure inposition to be wound, means for supporting a coil of magnetic strip,said ,means being spaced away from the winding structure a suflicientdistance to permit a relatively large loop of strip from said coil to bethreaded through said winding structure, said means comprisingoppositely rotating rollers engaging the inside and outside of the coilof strip to rotate the coil and drive the strip to unwind the coil andrewind the strip material into the larger loop, and means for biasingthe oppositely rotating rollers toward each other to grip the turns ofstrip located between the rollers.

2. A machine as set forth in claim 1 comprising means for collapsing theturns of the large loop upon the winding structure.

3. A machine as set forth in claim 1 including means for engaging theedge of the strip to prevent movement of the strip along the rollerswhich drive the strip.

4. A machine of the class described comprising means for unwinding aflatwise spirally wound coil of strip and simultaneously rewinding itinto a larger coil around an object out-side the origi-- nal coilcomprising oppositely driven rollers engaging the inside and outside ofthe coil, power driven rollers for collapsing the larger coil, and meansfor moving the coil-collapsing rollers inwardly as the coil collapses.

5. A machine for assembling a winding and a magnetic core 01' the woundtype, said machine including means for supporting the winding. meanscomprising a rotatable roller for supporting a wound coil of magneticstrip with its axis parallel to one side of the winding means forpressing the coil of strip against said roller, and means for rotatingsaid roller to unwind said coil and simultaneously rewind it around oneside of the winding.

6. A machine for assembling a winding and a magnetic core oi. the woundtype, said machine comprising means for supporting the winding and meanscomprising a roller for supporting a coil of magnetic strip material, asecond roller movable toward and away from the first roller, means forbiasing said rollers toward each other to grip the coil of striptherebetween, and means for rotating one of said rollers to unwind saidcoil and simultaneously rewind it around one side of the winding.

7. A machine for assembling a winding and a magnetic core of the woundtype, said machine comprising means for supporting the winding at agiven position, means for supporting a wound coil of magnetic materialbeside said position, I

means for rotating said coil to unwind it into a loop around one side ofthe winding and means for guiding said loop.

8. A machine for assembling, a winding and a magnetic core of the woundtype comprising a supporting table, a roller mounted for rotation onsaid table, a second roller biased toward the first roller, meansarranged to move said roller against its bias to separate the rollers,said second roller being removably mounted to permit a coil of magneticstrip to be placed on the table and the roller thereafter inserted intothe coil, said rollers being geared together to rotate in oppositedirections and means for rotating'the rollers to unwind said coil andsimultaneously wind it around one side of the winding.

9. A machine for assembling a winding and a magnetic core of the woundtype comprising means for winding a strip of magnetic material into arelatively large loop turning freely through the winding and means forcollapsing the turns of the large loop about the winding comprisingpower driven rollers and means for swinging said rollers into and out ofengagement with the turns to be collapsed, said means including yieldingmeans to permit of yielding engagement between said rollers and thesides of theloop.

10. A machine for assembling a winding and a magnetic core 01' the woundtype comprising a supporting table, a winding head and means foradjusting the winding head vertically with respect to the table, meansfor pivotally mounting the winding in the winding head and securing itin adjusted pivotal positions, means rotatably mounted on the table forrotating a strip of magnetic material through the winding and means foradjusting the winding head longitudinally of the table to vary thedistance between the winding and said rotatable means.

JOHN C. GRANFIELD.

